1. Field of the Invention
The invention relates to processes for manufacturing propynol from acetylene and formaldehyde.
2. Discussion of the Background
Propynol is used for synthesizing polyacetylenes and other natural substances. It is also used as a corrosion protection agent in the electroplating industry.
Propynol is produced in small amounts as a by-product in the production of 1,4-butynediol from formaldehyde and acetylene.
In the known processes for producing propynol, the starting materials are also formaldehyde and acetylene. In these processes the reaction of propynol with formaldehyde to form 1,4-butynediol is suppressed by the use of special reaction conditions. For example, German Pat. No. 1,174,765 discloses the use of N-methylpyrrolidone, which is a good solvent for acetylene and therefore enables a high acetylene concentration.
The reaction of acetylene and formaldehyde in the presence of copper acetylide leads principally to propynol, according to German Pat. No. 1,174,765. Separation out of the high boiling solvent however is technically complex and cost-intensive.
According to German Pat. No. 1,284,964, acetylene and formaldehyde can be reacted, with the aid of copper acetylide on a support, to form 1,4-butynediol and propynol. The two products are formed in comparable amounts. Formaldehyde dimethylacetal is noted as a solvent, but the preferred solvent is said to be butyrolactone. The dissolution is carried out under cooling, but requires increasingly high pressures, which represent a major safety risk.
The underlying problem in the production of propynol is the absence of a process permitting the production of propynol from acetylene and formaldehyde at decreased cost and with increased process safety.